1. Field of the Invention
The present invention relates generally to an apparatus and method for space-time coding in a multiple-antenna system, and, in particular, to a space-time coding apparatus and method for flexibly adjusting diversity/multiplexing orders in a multiple-antenna system.
2. Description of the Related Art
A variety of multimedia services for a wireless environment are demanded as the wireless mobile communication market continues its rapid growth. In addition, large-capacity data must be transmitted at a high speed in order to provide these multimedia services in wireless communication systems. Therefore, increasing attention is being drawn to a multiple-antenna system (e.g., a Multiple Input Multiple Output (MIMO) system) for increasing a data transmission rate using limited radio resources.
Compared to a single-antenna system, the multiple-antenna system can increase transmission reliability and a transmission rate without allocating additional frequencies or transmission power. That is, the multiple-antenna system can increase transmission reliability by achieving a diversity gain according to the number of transmitter/receiver (TX/RX) antennas, or can increase a transmission rate by simultaneously transmitting a plurality of signal sequences. Also, the multiple-antenna system can increase both the transmission reliability and the transmission rate using the hybrid scheme.
In order to achieve a lower error rate, the multiple-antenna system uses a space-time coding scheme that extends coding of the time domain to the space domain. In this context, the multiple-antenna system uses Alamouti space-time codes for obtaining a diversity effect and Bell Labs Layered Space-Time (BLAST) codes for obtaining a multiplexing effect. Also, the multiple-antenna system may use hybrid space-time codes for a trade-off between the diversity effect and the multiplexing effect.
A transmitter of the multiple-antenna system generates and stores space-time codes suitable for channel environments applicable to the multiple-antenna system. Based on channel information received from a corresponding receiver, the transmitter selects a space-time code, which is suitable for channel environments for providing a service to a receiver, in order to perform space-time coding.
This, however, complicates feedback information transmitted from the receiver to the transmitter and also wastes memory in the transmitter.